Micronutrient release and bioavailability during enhanced rock weathering in soils

Overview

Enhanced Rock Weathering (ERW) involves applying finely-ground silicate rock to agricultural soils to simultaneously sequester CO2 and fertilize crops. While ERW is increasingly recognized as a promising carbon drawdown strategy, a critical knowledge gap remains: the behavior and bioavailability of micronutrients released during the weathering process are completely unknown. Without this understanding, it is impossible to determine whether ERW will succeed as either a climate mitigation or agricultural amendment strategy.

This research addresses that gap by systematically tracking micronutrients such as iron, zinc, boron, manganese, molybdenum, copper, and chloride through soil column experiments. The work will determine which soil phases these elements partition into, directly influencing their availability to crops and the overall effectiveness of ERW as a soil management practice.

Technical specifications

Research approach:

• Laboratory soil column experiments with controlled drip-water systems, comparing ERW-amended columns against control columns over several months
• Effluent water analysis for elemental concentrations, with emphasis on critical micronutrients (Fe, Zn, B, Mn, Mo, Cu, Cl)
• Post-experiment soil analysis using preferential leaching techniques to isolate exchangeable, oxide, and clay phases
• Saturation-state modelling to identify secondary mineral formation
• Correlation of micronutrient behavior with application rate and grain size of ERW amendments

Key features:

• Builds on established experimental methods for tracking water and soil chemical changes during soil amendment
• Extends existing expertise in CO2 drawdown measurement and clay formation analysis during ERW
• Complements prior work on toxic heavy metal behavior with new focus on beneficial micronutrients
• Provides actionable data on application rates and grain sizes for practical ERW deployment

Technology readiness level

This research is at an early-to-mid experimental stage. Prior laboratory and field work has validated that ERW affects CO2 levels and plant growth, and soil column experiments have already demonstrated measurable dissolution rates, CO2 drawdown, and clay formation. The team has also examined heavy metal behavior during ERW. The current proposal extends these validated methods to the unexplored domain of micronutrient partitioning, representing a targeted scientific study rather than a commercialized technology. The laboratory experiments and modelling planned here will generate foundational data needed to assess ERW's viability as both a carbon sequestration method and a crop fertilization strategy.